I drilled two holes in the rib then used a jewelers file to open up the figure eight looking hole into an oval. Filed it to fit a Glock tritium sight then mounted it up. The poors man’s NOD!I bought a fiber optic front sight from the Sports Center here in Perry for mine. It's a setup with the little green tube thing that sits in a bracket that has magnets . I went ahead and glued it to mine.